The botanical literature provides meager details for seeds and ovules of our two species. The above images show great variation in color, size, shape and texture for both. The seeds of a given bush, however, tend to vary only in size. The seeds of B. trifoliolata are predominately yellowish-tan (like those on the left); those of the B. swaseyi, generally somewhat darker, and with no clear dominant color type. In comparing a large number of seeds, I noted greater variation in shape and size for B. trifoliolata, which I attribute to the relatively smaller ovary of B. trifoliolata - thus accommodating more mature ovules in the limited space. Black seeds - note the references below - were neither typical within any berry or any bush nor did they ever germinate. Rather these often seemed to reflect fungal or other damage within the carpel.
Since I am of the opinion that numerous individuals within my populations of both species seem to support massive, long-term introgressive hybridization, I cannot dismiss the possibility that both the variation and the differences between my observations and those in the literature cited below reflect this hybridization, and, in the case of B. trifoliolata, would only be typical for areas in which both species coexist.
Seeds 1-10, tan to red-brown or black; aril absent.and Ahrendt 1961:
Only dark seeds have been recorded in Mahonia. [p. 21]My own data indicate that the number of fertile seeds (i.e., those which are not black and do not float) counted for B. swaseyi fruits ranged from 1 to 10, with only one instance of 11; for B. trifoliolata and hybrids, 1-9. Carpel size did not seem to play a role in determining the number of seeds. The number of ovules was found to be significantly greater than indicated by Ahrendt.
Section Horridae ...
Ovules (4-) 5-9 (-18)
[in Key to Sect. Horridae, B. swaseyi and three others are distinguished from M. pinifolia by]
Ovules 4-8
[in description of B. swaseyi]
Ovules 5-7
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| B. swaseyi (S21) | B. trifoliolata (T22) |
| Placentation with developed funiculi | |
seeds brown, plump, about 3.5 mm. long (Correll & Johnston 1970)
seeds [not] red brown [RTH: Ahrendt's key uses this feature for M. higgensae, specifically to distinguish it from M. swaseyi]
ovules 5-7 (Ahrendt 1961)
seeds reddish-brown to brownish-black, vernicose, 3-4 mm. long (Correll & Johnston 1970)
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| B. trifoliolata (mid May) | B. swaseyi (June 26) |
| Typical seeds collected from ripe fruits of numerous plants. | |
My data differ in numerous details from the above color descriptions in both Correll & Johnston and Ahrendt. I found no significant differences in seed length or 'plumpness' - if any, the seeds of B. swaseyi (range 3.1 - 4.8 mm.) tend to be longer and less plump than those of B. trifoliolata (range 3.1 - 4.5). Seeds of both species appear to be vernicose, although B. swaseyi is generally less glossy.